Discrete time loop based thermal control

Abstract

In an embodiment, a circuit includes: an error amplifier; a temperature sensor, wherein the temperature sensor is coupled to the error amplifier; a discrete time controller coupled to the error amplifier, wherein the discrete time controller comprises digital circuitry; a multiple bits quantizer coupled to the discrete time controller, wherein the multiple bits quantizer produces a digital code output; and a heating array coupled to the multiple bits quantizer, wherein the heating array is configured to generate heat based on the digital code output.

What is claimed is: 
     
       1. A circuit, comprising:
 an error amplifier; 
 a temperature sensor coupled to an input of the error amplifier; 
 a discrete time controller coupled to an output of the error amplifier, wherein the discrete time controller comprises digital circuitry; 
 a multiple bits quantizer coupled to an output of the discrete time controller, wherein the multiple bits quantizer produces a digital code output based on the output of the discrete time controller; and 
 a heating array coupled to an output of the multiple bits quantizer, wherein the heating array is configured to generate heat based on the digital code output that controls different switches in the heating array, and 
 wherein the discrete time controller is coupled to the heating array via the multiple bits quantizer. 
 
     
     
       2. The circuit of  claim 1 , wherein the discrete time controller is an integrator controller. 
     
     
       3. The circuit of  claim 2 , wherein the integrator controller comprises an operational amplifier with a first capacitor between an inverting input and an output. 
     
     
       4. The circuit of  claim 3 , wherein, at the operational amplifier, the inverting input is connected with a switch and a non-inverting input is coupled to ground. 
     
     
       5. The circuit of  claim 4 , wherein, the switch is coupled to a second switch and a second capacitor. 
     
     
       6. The circuit of  claim 5 , wherein the switch is driven by a first clock signal and the second switch is driven by a second clock signal, wherein the first clock signal and the second clock signal are non-overlapping clock signals with a same period. 
     
     
       7. The circuit of  claim 1 , wherein the digital code output comprises multiple bits that are each configured to control different heating elements of the heating array. 
     
     
       8. The circuit of  claim 1 , wherein the discrete time controller is a proportional and integrator controller. 
     
     
       9. The circuit of  claim 1 , wherein the discrete time controller is a proportional integral derivative controller. 
     
     
       10. The circuit of  claim 1 , wherein the heating array comprises multiple heating elements, wherein each heating element comprises a resistor with one end coupled to a voltage source and another end coupled to a switch to ground. 
     
     
       11. A circuit, comprising:
 an error amplifier; 
 a sensor, wherein the sensor is coupled to the error amplifier; 
 a discrete time controller coupled to an output of the error amplifier, 
 a quantizer coupled to the discrete time controller, wherein the quantizer generates a digital code based on an output of the discrete time controller; and 
 an array coupled to the quantizer, wherein the digital code is utilized by the array to control different switches within the array, and 
 wherein the discrete time controller is coupled to the array via the quantizer. 
 
     
     
       12. The circuit of  claim 11 , wherein the array is a heating array. 
     
     
       13. The circuit of  claim 12 , wherein the heating array comprises heating elements that are monotonic. 
     
     
       14. The circuit of  claim 11 , wherein the sensor is a temperature sensor and wherein the array is a heating array. 
     
     
       15. The circuit of  claim 11 , wherein the quantizer is a multiple bit quantizer. 
     
     
       16. A method, comprising:
 producing an output of a process based on an reference value input, wherein the output is a temperature produced by a heating array, comprising a plurality of heating coils; 
 determining an output measurement value based on the output using a temperature sensor embedded within the heating array; 
 determining an error between the output measurement value and the reference value input using an error amplifier; 
 controlling the process based on the error using a discrete time controller that generates a control signal; and 
 performing the process with a quantizer, wherein the quantizer utilizes the control signal to generate a digital code, and wherein the digital code individually controls different coils of the heating array. 
 
     
     
       17. The method of  claim 16 , wherein the process is performed by a multiple bit quantizer. 
     
     
       18. The method of  claim 16 , further comprising turning the heating array on or off based on the process. 
     
     
       19. The method of  claim 16 , further comprising turning different coils of the heating array on or off based on the digital code produced by a multiple bit quantizer. 
     
     
       20. The method of  claim 16 , wherein the discrete time controller is implemented in digital circuitry.